Method of forming a fiber made of peptide nanostructures

ABSTRACT

A method of forming a fiber made of peptide nanostructures is disclosed. The method comprises: providing peptide nanostructures in solution, and fiberizing the solution thereby forming at least one fiber of the peptide nanostructures. Also disclosed are methods of forming films and other articles using the peptide nanostructures.

RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.11/659,150 filed on Oct. 17, 2008, which is a National Phase of PCTPatent Application No. PCT/IL2005/000589 having International FilingDate of Jun. 5, 2005, which claims the benefit of priority of U.S.Provisional Patent Application No. 60/592,523 filed on Aug. 2, 2004. Thecontents of the above applications are all incorporated herein byreference.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to articles made of nanostructures and,more particularly, to articles made of peptide nanostructures havingsizes at least in the micrometer scale.

Material sciences involve the understanding of material characteristicsas well as the development of new materials. Industrial and academicneeds encourage material scientists to develop new materials havingsuperior mechanical, electrical, optical and/or magnetic properties formany applications. Modern material sciences focus on the investigationof polymers, ceramics and semiconductors in many fluidic as well assolid forms including fibers, thin films, material bulks and the like.

Various manufacturing processes are known in the art for makingsynthetic fibers. Many synthetic fibers are produced by extrusionprocesses, in which a thick viscous liquid polymer precursor orcomposition is forced through one or more tiny holes of a spinneret toform continuous filaments of semi-solid polymer. As the filaments emergefrom the holes of a spinneret, the liquid polymer converts first to arubbery state which then is solidified. The process of extruding andsolidifying filaments is generally known as spinning.

Wet spinning processes are typically employed with fiber-formingsubstances that have been dissolved in a solvent. Wet spinningtechniques are preferred for spinning of high molecular weightpolyamides. The spinnerets forming the filaments are submerged in a wetchemical bath, and as the filaments of the fiber-forming substancesemerge from the spinnerets, they are induced to precipitate out of thesolution and solidify.

In gel spinning, the polymer is not in a true liquid state duringextrusion. The polymer chains are bound together at various points inliquid crystal form. This produces strong inter-chain forces in theresulting filaments that can significantly increase the tensile strengthof the fibers. In addition, the liquid crystals are aligned along thefiber axis by the shear forces during extrusion. The filaments emergewith high degree of orientation relative to each other, furtherenhancing the strength. Typically, in gel spinning, the filaments firstpass through air and then cooled in a liquid bath.

In dry spinning, the polymer is dissolved in a volatile solvent and thesolution is pumped through the spinneret. As the fibers exit thespinneret, air is used to evaporate the solvent such that the fiberssolidify and can be collected on a take-up wheel.

In melt spinning the polymer is melted and pumped through the spinneret.The molten fibers are cooled, solidified, and collected on a take-upwheel. Stretching of the fibers in both the molten and solid statesprovides for orientation of the polymer chains along the fiber axis.

Dispersion spinning is typically employed when the polymer having andinfusible, insoluble and generally intractable characteristics. In thistechnique, the polymer is dispersed as fine particles in a chemicalcarrier that permit extrusion into fiber. The dispersed polymer is thencaused to coalesce by a heating process and the carrier is removed by athermal or chemical procedure.

Reaction spinning processes involve the formation of filaments frompre-polymers and monomers. The pre-polymers and monomers are furtherpolymerized and cross-linked after the filament is formed. The reactionspinning process begins with the preparation of a viscous spinningsolution, which is prepared by dissolving a low molecular weight polymerin a suitable solvent and a reactant. The spinning solution is thenforced through the spinneret into a solution or being combined with athird reactant. The primary distinguishable characteristic of reactionspinning processes is that the final cross-linking between the polymermolecule chains in the filament occurs after the fibers have been spun.Post-spinning steps typically include drying and lubrication.

In tack spinning, a polymeric material in a tacky state is interposedbetween a foundation layer and a temporary anchorage surface. Being in atacky state, the polymeric material adheres to the foundation layer andthe temporary anchorage surface. The foundation layer is then separatedfrom the temporary anchorage surface to produce fibers of the polymericmaterial. The fibers are hardened by thermal or chemical treatment, andseparated from the temporary anchorage surface.

In electrospinning, a fine stream or jet of liquid is produced bypulling a small amount of charged liquefied polymer through space usingelectrical forces. The produced fibers are hardened and collected on asuitably located precipitation device to form a nonwoven article. In thecase of a liquefied polymer which is normally solid at room temperature,the hardening procedure may be mere cooling, however other proceduressuch as chemical hardening or evaporation of solvent may also beemployed.

Other processes for manufacturing polymeric articles include filmblowing and injection molding.

In film blowing, an extruder is used to melt the polymer and pump itinto a tubular die. Air blown into the center of the tube causes themelt to expand in the radial direction. The melt in thus extended inboth radial and down-stream direction. The formed film is then collectedby an arrangement of rollers.

In injection molding, a reciprocating or rotating screw both meltspolymer pellets and provides the pressure required to inject the meltinto a cold mold. The cold mold provides the article the desired shape.

In the area of thin film production, a well-known method for producingand depositing monolayers is the Langmuir-Blodgett method. In thismethod a monolayer of amphiphilic molecules is formed at the surface ofa tank filled with a liquid sub-phase such as water. Amphiphilicmolecules are those having a hydrophobic first end and a hydrophilicsecond end lined up side by side in a particular direction. In theLangmuir-Blodgett method, a solution of amphiphilic molecules dissolvedin a solvent which is not miscible with the sub-phase liquid in the tankis spread onto the liquid surface. When the solvent evaporates, aloosely packed monolayer is formed on the surface of the sub-phase. Atransition of the monolayer thus formed from a state of gas or liquid toa solid state is then achieved by compressing surface area of the layerto a predetermined surface pressure. The resulting monolayer isdeposited onto the surface of a substrate by passing the substratethrough the compressed layer while maintaining the layer at apredetermined surface pressure during the period of deposition.

Another method for producing a monolayer is known as self-assembling ofmolecules. In this method, a monolayer film is generated as a result ofadsorption and bonding of suitable molecules (e.g., fatty acids, organicsilicon molecules or organic phosphoric molecules) on a suitablesubstrate surface. The method typically involves solution depositionchemistry in the presence of water.

Over the years, extensive efforts were made to develop row materialswhich can be used for manufacturing fiber and films by the abovetechniques to provide articles having enhanced and/orapplication-specific characteristics. For example, one of the moststudied natural fibrillar system is silk [Kaplan D L, “Fibrousproteins—silk as a model system,” Polymer degradation and stability,59:25-32, 1998]. There are many forms of silk, of which spider silk ofNephila clavipas (the golden orb weaver) is regarded as nature's highperformance fiber, with a remarkable combination of strength,flexibility, and toughness. Although assembled by non-covalentinteractions, silk is stronger than steel per given fibrillar diameterbut, at the same time, is much more flexible. Due to its superiormechanical properties, the spider silk can be used in many areasrequiring the combination of high mechanical strength withbiodegradability, e.g., in tissue engineering applications [Kubik S.,“High-Performance Fibers from Spider Silk,” Angewandte ChemieInternational Edition, 41:2721-2723, 2002].

A known method of synthesizing spider silk material includes theintroduction of a spider silk gene into a heterologous gene expressionsystem and the secretion of spider silk protein therefrom. The proteinis then processed, typically by electrospinning, to produce a fiber ofenhanced mechanical properties [Jin H J, Fridrikh S V, Rutledge G C andKaplan D L, “Electrospinning Bombyx mori silk with poly(ethyleneoxide),” Biomacromolecules, 3:1233-1239, 2002].

Recently, electrospinning has been employed to fabricate virus-basedcomposite fibers hence to mimic the spinning process of silk spiders[Lee S and Belcher A M, “Virus-Based Fabrication of Micro- andNanofibers Using Electrospinning,” Nano letters, 4:388-390, 2004]. Inthis study, M13 virus was genetically modified to bind conductive andsemiconductor materials, and was thereafter subjected to anelectrospinning process to provide conductive and semiconductor fibers.

Other than synthesized spider silk, the electrospinning process can beapplied on a diversity of polymers including polyamides, polyactides andwater soluble polymer such as polyethyleneoxide [Huang Z M, Zhang Y Z,Kotaki M and Ramakrishna S., “A review on polymer nanofibers byelectrospinning and their applications in nanocomposites,” CompositesScience and technology, 63:2223-2253, 2003]. Heretofore, about 50 typesof polymers have been successfully electrospun.

Electrospinning has also been used with carbon nanotubes to obtainsuper-though carbon-nanotube fibers [Dalton A B et al., “Super-toughcarbon-nanotube fibres—These extraordinary composite fibres can be woveninto electronic textiles,” Nature, 423:703, 2003]. By modifying afamiliar method for carbon nanotubes fibers [Vigolo et al., “MacroscopicFibers and Ribbons of Oriented Carbon Nanotubes,” Science, 17:1331-1334,2000] the researchers were able to spin a reel of nanotube gel fiber andthen convert it into 100 m length of solid nanotube composite fiber. Theresulting fibers were tougher than any other known natural or syntheticorganic fiber.

However, carbon nanotubes in general and carbon-nanotube fibers inparticular suffer from structural deviations. Although deviations instructure can be introduced in a “controlled” manner under specificconditions, frequent uncontrollable insertion of such defects result inspatial structures with unpredictable electronic, molecular andstructural properties. In addition, the production process of carbonnanotubes is very expensive and presently stands hundreds of U.S.dollars per gram.

Other known nanostructures are peptide-based nanotubular structures,made through stacking of cyclic D-, L-peptide subunits. These peptidesself-assemble through hydrogen-bonding interactions into nanotubules,which in-turn self-assemble into ordered parallel arrays of nanotubes.The number of amino acids in the ring determines the inside diameter ofthe nanotubes obtained. Such nanotubes have been shown to formtransmembrane channels capable of transporting ions and small molecules[Ghadiri, M. R. et al., Nature 366, 324-327 (1993); Ghadiri, M. R. etal., Nature 369, 301-304 (1994); Bong, D. T. et al., Angew. Chem. Int.Ed. 40:988-1011, 2001].

More recently, surfactant-like peptides that undergo spontaneousassembly to form nanotubes with a helical twist have been discovered.The monomers of these surfactant peptides, like lipids, have distinctivepolar and nonpolar portions. They are composed of 7-8 residues,approximately 2 nm in length when fully extended, and dimensionallysimilar to phospholipids found in cell membranes. Although the sequencesof these peptides are diverse, they share a common chemical property,i.e., a hydrophobic tail and a hydrophilic head. These peptidenanotubes, like carbon and lipid nanotubes, also have a very highsurface area to weight ratio. Molecular modeling of the peptidenanotubes suggests a possible structural organization [Vauthey (2002)Proc. Natl. Acad. Sci. USA 99:5355; Zhang (2002) Curr. Opin. Chem. Biol.6:865]. Based on observation and calculation, it is proposed that thecylindrical subunits are formed from surfactant peptides thatself-assemble into bilayers, where hydrophilic head groups remainexposed to the aqueous medium. Finally, the tubular arrays undergoself-assembly through non-covalent interactions that are widely found insurfactant and micelle structures and formation processes.

Peptide based bis(N-α-amido-glycyglycine)-1,7-heptane dicarboxylatemolecules were also shown to be assembled into tubular structures[Matsui (2000) J. Phys. Chem. B 104:3383].

When the crystal structure of di-phenylalanine peptides was determined,it was noted that hollow nanometric channels are formed within theframework of the macroscopic crystal [Gorbitz et al., Chemistry7(23):5153-9, 2001]. However, no individual nanotubes could be formed bycrystallization, as the crystallization conditions used in this studyincluded evaporation of an aqueous solution at 80° C. No formation ofdiscrete nano-structures was reported under these conditions.

International Patent Application Nos. IL03/01045 and IL2004/000012 (seealso Reches M and Gazit E, “Casting metal nanowires within discreteself-assembled peptide nanotubes,” Science, 300:625-627, 2003), disclosea new procedure for making peptide nanostructures that show manyultrastructural and physical similarities to carbon nanotubes. Thesepeptide nanostructures are self assembled by diphenylalanine, the corerecognition motif of the β-amyloid peptide [Findeis et al., “Peptideinhibitors of beta amyloid aggregation,” Biochemistry, 38:6791, 1999;Tjernberg et al., “Arrest of -Amyloid Fibril Formation by a PentapeptideLigand,” J. Biol. Chem., 271:8545-8548, 1996; and Soto et al.,“Beta-sheet breaker peptides inhibit fibrillogenesis in a rat brainmodel of amyloidosis: implications for Alzheimer's therapy,” NatureMedicine, 4:822-826, 1998].

The self-assembled peptide nanostructures are well ordered assemblies ofvarious shapes with persistence length on the order of micrometers. Theformation of the peptide nanostructures is very efficient and thenanostructures solution is very homogeneous. Similar to carbonnanotubes, the peptide nanostructures are formed as individual entities.For industrial applications, the self-assembled peptide nanostructuresare favored over carbon nanotubes and spider silk from standpoint ofcost, production means and availability.

There is thus a widely recognized need for, and it would be highlyadvantageous to have macroscopic and microscopic articles exploiting theadvantages of self-assembled peptide nanostructures.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided amethod of forming a fiber made of peptide nanostructures, the methodcomprising providing peptide nanostructures in solution, and fiberizingthe solution thereby forming at least one fiber of the peptidenanostructures.

According to further features in preferred embodiments of the inventiondescribed below, the fiberizing is by an electrospinning process, a wetspinning process, a dry spinning process, a gel spinning process, adispersion spinning process, a reaction spinning process or a tackspinning process.

According to another aspect of the present invention there is provided amethod of forming a film of peptide nanostructures, comprising:dissolving peptide molecules in an organic solvent; adding an aqueoussolvent to the organic solvent such that an interface is formed betweenthe organic solvent and the aqueous solvent; and incubating the organicand the aqueous solvents under conditions which allow the peptidemolecules to form a film of peptide nano structures in the interface.

According to still further features in the described preferredembodiments the organic solvent is an aromatic solvent, such as but notlimited to benzene. According to still further features in the describedpreferred embodiments the hydrophilic solvent is water.

According to yet another aspect of the present invention there isprovided a method of forming at least one layer of peptidenanostructures, comprising: placing peptide nanostructures in an organicsolvent; applying at least one droplet of the organic solvent onto asurface of an hydrophilic solvent; and applying pressure onto the atleast one droplet of the organic solvent, so as to form at least onelayer of peptide nanostructures on the surface of the hydrophilicsolvent.

According to further features in preferred embodiments of the inventiondescribed below, the method further comprises transferring the at leastone layer of the peptide nanostructures to a substrate.

According to still further features in the described preferredembodiments the transferring of the layer(s) to the substrate iseffected by a Langmuir-Blodgett technique or a Langmuir-Schaeffertechnique.

According to still another aspect of the present invention there isprovided a method of forming an aligned array or film of peptidenanostructures. The method comprising: dissolving peptide molecules inan organic solvent; applying the organic solvent on a substrate; andincubating the substrate and the organic solvent under conditions whichallow the peptide molecules to form an aligned array or a film ofpeptide nanostructures on the substrate.

According to further features in preferred embodiments of the inventiondescribed below, the nanostructures are responsive to a magnetic field.According to still further features in the described preferredembodiments the method further comprises subjecting the substrate to amagnetic field.

According to further features in preferred embodiments of the inventiondescribed below, the nanostructures are responsive to an electric field.According to still further features in the described preferredembodiments the method further comprises subjecting the substrate to anelectric field.

According to still another aspect of the present invention there isprovided a method of forming a fiber made of peptide nanostructures, themethod comprising subjecting peptide nanostructures, in solution, to anelectric field so as to form at least one fiber of the peptidenanostructures.

According to further features in preferred embodiments of the inventiondescribed below, collecting the at least one fiber on a precipitationelectrode.

According to still further features in the described preferredembodiments the collecting of the fiber(s) comprises rotating theprecipitation electrode so as to wind the at least one fiber around theprecipitation electrode.

According to still further features in the described preferredembodiments the collecting of the fiber(s) comprises moving the at leastone fiber relative to the precipitation electrode so as to provide anonwoven mat of peptide nanostructures.

According to still further features in the described preferredembodiments the method further comprises unwinding the at least onefiber of the peptide nanostructure off the precipitation electrode.

According to an additional aspect of the present invention there isprovided a fiber comprising a plurality of peptide nanostructures asdescribed herein, the fiber being at least 100 nm in length.

According to still an additional aspect of the present invention thereis provided a nonwoven article comprising a plurality of electrospunfibers, wherein at least one of the plurality of electrospun fibers isthe fiber described herein.

According to yet a further aspect of the present invention there isprovided a thin film comprising at least one layer of peptidenanostructures as described herein, the thin film being at least 100 nm²in area size.

According to further features in preferred embodiments of the inventiondescribed below, each of the peptide nanostructures comprises no morethan 4 amino acids, at least one of the 4 amino acids being an aromaticamino acid.

According to still further features in the described preferredembodiments each of the 4 amino acids is independently selected from thegroup consisting of naturally occurring amino acids, synthetic aminoacids, β-amino acids, Peptide Nucleic Acid (PNA) and combinationsthereof.

According to still further features in the described preferredembodiments at least one of the 4 amino acids is a D-amino acid.

According to still further features in the described preferredembodiments at least one of the 4 amino acids is an L-amino acid.

According to still further features in the described preferredembodiments at least one of the peptide nanostructures comprises atleast two aromatic moieties.

According to still further features in the described preferredembodiments at least one of the peptide nanostructures is ahomodipeptide.

According to still further features in the described preferredembodiments each of the amino acids is the homodipeptide comprises anaromatic moiety, such as, but not limited to, substituted naphthalenyl,unsubstituted naphthalenyl, substituted phenyl or unsubstituted phenyl.

According to still further features in the described preferredembodiments the substituted phenyl is selected from the group consistingof pentafluoro phenyl, iodophenyl, biphenyl and nitrophenyl.

Thus, representative examples of the amino acids in the homopeptideinclude, without limitation, naphthylalanine, p-nitro-phenylalanine,iodo-phenylalanine and fluoro-phenylalanine.

According to still further features in the described preferredembodiments the homodipeptide is selected from the group consisting ofnaphthylalanine-naphthylalanine dipeptide,(pentafluoro-phenylalanine)-(pentafluoro-phenyl alanine)dipeptide,(iodo-phenylalanine)-(iodo-phenylalanine)dipeptide, (4-phenylphenylalanine)-(4-phenyl phenylalanine)dipeptide and(p-nitro-phenylalanine)-(p-nitro-phenylalanine)dipeptide.

According to still further features in the described preferredembodiments each of the peptide nanostructures comprises a plurality ofpolyaromatic peptides.

According to still further features in the described preferredembodiments each of the plurality of polyaromatic peptides comprises acomponent selected from the group consisting of a polyphenylalaninepeptide, a polytriptophane peptide, a polytyrosine peptide, anon-natural derivatives thereof and a combination thereof.

According to still further features in the described preferredembodiments each of the plurality of polyaromatic peptides comprises atleast 30 amino acids.

According to still further features in the described preferredembodiments the nanostructures at least partially enclose a materialtherein.

According to still further features in the described preferredembodiments the material is in a gaseous state.

According to still further features in the described preferredembodiments the material is in a condensed state.

According to still further features in the described preferredembodiments the material is selected from the group consisting of aconducting material, a semiconducting material, a thermoelectricmaterial, a magnetic material, a light-emitting material, a biomineral,a polymer and an organic material.

According to still further features in the described preferredembodiments the conducting material is selected from the groupconsisting of silver, gold, copper, platinum, nickel and palladium.

According to still further features in the described preferredembodiments the semiconducting material is selected from the groupconsisting of CdS, CdSe, ZnS and SiO₂.

According to still further features in the described preferredembodiments the magnetic material is a paramagnetic material.

According to still further features in the described preferredembodiments the paramagnetic material is selected from the groupconsisting of cobalt, copper, nickel and platinum.

According to still further features in the described preferredembodiments the magnetic material is a ferromagnetic material.

According to still further features in the described preferredembodiments the ferromagnetic material is selected from the groupconsisting of magnetite and NdFeB.

According to still further features in the described preferredembodiments the light-emitting material is selected from the groupconsisting of dysprosium, europium, terbium, ruthenium, thulium,neodymium, erbium, ytterbium and any organic complex thereof.

According to still further features in the described preferredembodiments the biomineral comprises calcium carbonate.

According to still further features in the described preferredembodiments the polymer is selected from the group consisting ofpolyethylene, polystyrene polyvinyl chloride and a thermoplasticpolymer.

According to still further features in the described preferredembodiments the thermoelectric material is selected from the groupconsisting of bismuth telluride, bismuth selenide, bismuth antimonytelluride and bismuth selenium telluride.

According to still further features in the described preferredembodiments the polymer is selected from the group consisting of apolynucleotide and a polypeptide.

The present invention successfully addresses the shortcomings of thepresently known configurations by providing a fiber, film, article andmethod of manufacturing the same. The fiber, film, article and method ofthe present invention enjoy properties far exceeding the prior art.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although methods and materialssimilar or equivalent to those described herein can be used in thepractice or testing of the present invention, suitable methods andmaterials are described below. In case of conflict, the patentspecification, including definitions, will control. In addition, thematerials, methods, and examples are illustrative only and not intendedto be limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, withreference to the accompanying drawings. With specific reference now tothe drawings in detail, it is stressed that the particulars shown are byway of example and for purposes of illustrative discussion of thepreferred embodiments of the present invention only, and are presentedin the cause of providing what is believed to be the most useful andreadily understood description of the principles and conceptual aspectsof the invention. In this regard, no attempt is made to show structuraldetails of the invention in more detail than is necessary for afundamental understanding of the invention, the description taken withthe drawings making apparent to those skilled in the art how the severalforms of the invention may be embodied in practice.

In the drawings:

FIG. 1 is a flowchart diagram of a method suitable for forming a fibermade of peptide nanostructures, according to a preferred embodiment ofthe present invention;

FIG. 2 is a flowchart diagram of a method suitable for forming a film ofpeptide nanostructures, according to a preferred embodiment of thepresent invention;

FIG. 3 is a flowchart diagram of a method suitable for forming one ormore layers of peptide nanostructures, according to another preferredembodiment of the present invention;

FIG. 4 is a flowchart diagram of a method suitable for forming an arrayor film of peptide nanostructures on a substrate, according to anotherpreferred embodiment of the present invention;

FIGS. 5A-C show a process of manufacturing a thin film in accordancewith preferred embodiments of the present invention;

FIG. 6 is a pressure-area isotherm obtained during manufacturing of athin film using Langmuir-Blodgett technique and in accordance withpreferred embodiments of the present invention;

FIGS. 7A-B are high-resolution scanning electron microscope images,showing a low magnification (FIG. 7A) and a high magnification (FIG. 7B)of an aligned array of peptide nanotubes formed on a substrate,according to the teaching of various exemplary embodiments of thepresent invention;

FIG. 8 is a schematic illustration of a chemical structure of anaphthylalanine-naphthylalanine (Nal-Nal) dipeptide;

FIG. 9 is an electron microscope image of Nal-Nal tubularnanostructures; and

FIGS. 10A-D are electron microscope images of tubular and planarnanostructures assembled from the following aromatic-homodipeptides:(pentafluoro-phenylalanine)-(pentafluoro-phenylalanine) (FIG. 10A),(iodo-phenylalanine)-(iodo-phenylalanine) (FIG. 10B), (4-phenylphenylalanine)-(4-phenyl phenylalanine) (FIG. 10C), and(p-nitro-phenylalanine)-(p-nitro-phenylalanine) (FIG. 10D).

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is of a method which can be used for manufacturingarticles of peptide nanostructures. Specifically, the present inventioncan be used to manufacture fibers, films and other articles having sizesat least in the micrometer scale. The present invention is further offibers, films and other articles made of peptide nanostructures.

The principles and operation of a method according to the presentinvention may be better understood with reference to the drawings andaccompanying descriptions.

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not limited in its applicationto the details of construction and the arrangement of the components setforth in the following description or illustrated in the drawings. Theinvention is capable of other embodiments or of being practiced orcarried out in various ways. Also, it is to be understood that thephraseology and terminology employed herein is for the purpose ofdescription and should not be regarded as limiting.

Referring now to the drawings, FIG. 1 is a flowchart diagram of a methodsuitable for forming a fiber made of peptide nanostructures. The methodbegins at step 10 and continues to step 12 in which peptidenanostructures in solution are provided.

As used herein the phrase “nanostructure” refers to a structure having adiameter or a cross-section of less than 1 μm (preferably less than 500nm, more preferably less than about 50 nm, even more preferably lessthan about 5 nm). The length of the nanostructure of the presentembodiments is preferably at least 1 nm, more preferably at least 10 nm,even more preferably at least 100 nm and even more preferably at least500 nm. It will be appreciated, though, that the nanostructure of thepresent embodiments can be of infinite length (i.e., macroscopic fibrousstructures) and as such can be used in the fabrication of hyper-strongmaterials.

As used herein the term “about” refers to ±10%.

The solution can be prepared, for example, by placing or dissolving thenanostructures in an organic solvent, which is preferably an aromaticsolvent, such as, but not limited to, benzene. Additionally, thesolution may contain polymeric additives, or any other material suitablefor forming fibers therefrom.

The method continues to step 14 in which the solution is fiberized toform at least one fiber of peptide nanostructures. The solution can befiberized by any conventional process, such as, but not limited to, aspinning process, a blowing process, an injection process and the like.Contemplated spinning processes include, without limitation, wetspinning process, gel spinning process, dry spinning process, dispersionspinning process, reaction spinning process, tack spinning process andelectrospinning process. These spinning processes are described in theBackground section above and can be found in many text books andpatents, see, e.g., U.S. Pat. Nos. 3,737,508, 3,950,478, 3,996,321,4,189,336, 4,402,900, 4,421,707, 4,431,602, 4,557,732, 4,643,657,4,804,511, 5,002,474, 5,122,329, 5,387,387, 5,667,743, 6,248,273 and6,252,031 the contents of which are hereby incorporated by reference.Representative examples of spinning processes in various preferredembodiments of the present invention are further detailed hereinunder.

The method ends at step 16.

Peptide nanostructures which can be used according to the presentembodiments include nanostructures composed of surfactant like peptidesand cyclic D-, L-peptide subunits. The nanostructures can beself-assembled from a plurality of peptides. Preferably, but notobligatorily, the peptides include no more than 4 amino acids of whichat least one is an aromatic amino acid.

In various exemplary embodiments of the embodiments the peptidescomprise a dipeptide or a tripeptide. The shape of the nanostructuresdepends on the rigidity of the molecular structure of the peptide used.For example a plurality of diphenylglycine peptides which offer similarmolecular properties as diphenylalenine peptides albeit with a lowerdegree of rotational freedom around the additional C—C bond and a highersteric hindrence self-assemble into nano-spheres, while a plurality ofdiphenylalenine peptides self-assemble into nano-tubes.

The present embodiments also envisages nanostructures which are composedof a plurality of polyaromatic peptides being longer than the abovedescribed (e.g., 50-136 amino acids).

As used herein the phrase “polyaromatic peptides” refers to peptideswhich include at least 80%, at least 85% at least 90%, at least 95% ormore, say 100% aromatic amino acid residues. These peptides can behomogenic (e.g., polyphenylalanine) or heterogenic of at least 10, atleast 15, at least 20, at least 25, at least 30, at least 35, at least40, at least 45, at least 50, at least 55, at least 60, at least 65, atleast 70, at least 75, at least 80, at least 85, at least 90, at least95, at least 100, at least 105, at least 110, at least 120, at least125, at least 130, at least 135, at least 140, at least 145, at least150, at least 155, at least 160, at least 170, at least 190, at least200, at least 300 or at least 500 amino acids.

The term “peptide” as used herein encompasses native peptides (eitherdegradation products, synthetically synthesized peptides or recombinantpeptides) and peptidomimetics (typically, synthetically synthesizedpeptides), as well as peptoids and semipeptoids which are peptideanalogs, which may have, for example, modifications rendering thepeptides more stable while in a body or more capable of penetrating intocells. Such modifications include, but are not limited to N terminusmodification, C terminus modification, peptide bond modification,including, but not limited to, CH2-NH, CH2-S, CH2-S═O, O═C—NH, CH2-O,CH2-CH2, S═C—NH, CH═CH or CF═CH, backbone modifications, and residuemodification. Methods for preparing peptidomimetic compounds are wellknown in the art and are specified, for example, in Quantitative DrugDesign, C. A. Ramsden Gd., Chapter 17.2, F. Choplin Pergamon Press(1992), which is incorporated by reference as if fully set forth herein.Further details in this respect are provided hereinunder.

Peptide bonds (—CO—NH—) within the peptide may be substituted, forexample, by N-methylated bonds (—N(CH3)-CO—), ester bonds(—C(R)H—C—O—O—C(R)—N—), ketomethylen bonds (—CO—CH2-), α-aza bonds(—NH—N(R)—CO—), wherein R is any alkyl, e.g., methyl, carba bonds(—CH2-NH—), hydroxyethylene bonds (—CH(OH)—CH2-), thioamide bonds(—CS—NH—), olefinic double bonds (—CH═CH—), retro amide bonds (—NH—CO—),peptide derivatives (—N(R)—CH2-CO—), wherein R is the “normal” sidechain, naturally presented on the carbon atom.

These modifications can occur at any of the bonds along the peptidechain and even at several (2-3) at the same time.

Natural aromatic amino acids, Trp, Tyr and Phe, may be substituted forsynthetic non-natural acid such as Phenylglycine, TIC, naphthylalanine(Nal), ring-methylated derivatives of Phe, halogenated derivatives ofPhe or O-methyl-Tyr and β amino-acids

In addition to the above, the peptides of the present embodiments mayalso include one or more modified amino acids (e.g., thiolated orbiotinylated amino acids) or one or more non-amino acid monomers (e.g.,fatty acids, complex carbohydrates etc.). Also contemplated arehomodipeptides, and more preferably aromatic homodipeptides in whicheach of the amino acids comprises an aromatic moiety, such as, but notlimited to, substituted or unsubstituted naphthalenyl and substituted orunsubstituted phenyl. The aromatic moiety can alternatively besubstituted or unsubstituted heteroaryl such as, for example, indole,thiophene, imidazole, oxazole, thiazole, pyrazole, pyridine, pyrimidine,quinoline, isoquinoline, quinazoline, quinoxaline, and purine

When substituted, the phenyl, naphthalenyl or any other aromatic moietyincludes one or more substituents such as, but not limited to, alkyl,trihaloalkyl, alkenyl, alkynyl, cycloalkyl, aryl, heteroaryl,heteroalicyclic, halo, nitro, azo, hydroxy, alkoxy, thiohydroxy,thioalkoxy, cyano, and amine.

As used herein, the term “alkyl” refers to a saturated aliphatichydrocarbon including straight chain and branched chain groups.Preferably, the alkyl group has 1 to 20 carbon atoms. The alkyl groupmay be substituted or unsubstituted. When substituted, the substituentgroup can be, for example, trihaloalkyl, alkenyl, alkynyl, cycloalkyl,aryl, heteroaryl, heteroalicyclic, halo, nitro, azo, hydroxy, alkoxy,thiohydroxy, thioalkoxy, cyano, and amine.

A “cycloalkyl” group refers to an all-carbon monocyclic or fused ring(i.e., rings which share an adjacent pair of carbon atoms) group whereinone of more of the rings does not have a completely conjugatedpi-electron system. Examples, without limitation, of cycloalkyl groupsare cyclopropane, cyclobutane, cyclopentane, cyclopentene, cyclohexane,cyclohexadiene, cycloheptane, cycloheptatriene, and adamantane. Acycloalkyl group may be substituted or unsubstituted. When substituted,the substituent group can be, for example, alkyl, trihaloalkyl, alkenyl,alkynyl, cycloalkyl, aryl, heteroaryl, heteroalicyclic, halo, nitro,azo, hydroxy, alkoxy, thiohydroxy, thioalkoxy, cyano, and amine.

An “alkenyl” group refers to an alkyl group which consists of at leasttwo carbon atoms and at least one carbon-carbon double bond.

An “alkynyl” group refers to an alkyl group which consists of at leasttwo carbon atoms and at least one carbon-carbon triple bond.

An “aryl” group refers to an all-carbon monocyclic or fused-ringpolycyclic (i.e., rings which share adjacent pairs of carbon atoms)groups having a completely conjugated pi-electron system. Examples,without limitation, of aryl groups are phenyl, naphthalenyl andanthracenyl. The aryl group may be substituted or unsubstituted. Whensubstituted, the substituent group can be, for example, alkyl,trihaloalkyl, alkenyl, alkynyl, cycloalkyl, aryl, heteroaryl,heteroalicyclic, halo, nitro, azo, hydroxy, alkoxy, thiohydroxy,thioalkoxy, cyano, and amine.

A “heteroaryl” group refers to a monocyclic or fused ring (i.e., ringswhich share an adjacent pair of atoms) group having in the ring(s) oneor more atoms, such as, for example, nitrogen, oxygen and sulfur and, inaddition, having a completely conjugated pi-electron system. Examples,without limitation, of heteroaryl groups include pyrrole, furane,thiophene, imidazole, oxazole, thiazole, pyrazole, pyridine, pyrimidine,quinoline, isoquinoline and purine. The heteroaryl group may besubstituted or unsubstituted. When substituted, the substituent groupcan be, for example, alkyl, trihaloalkyl, alkenyl, alkynyl, cycloalkyl,aryl, heteroaryl, heteroalicyclic, halo, nitro, azo, hydroxy, alkoxy,thiohydroxy, thioalkoxy, cyano, and amine.

A “heteroalicyclic” group refers to a monocyclic or fused ring grouphaving in the ring(s) one or more atoms such as nitrogen, oxygen andsulfur. The rings may also have one or more double bonds. However, therings do not have a completely conjugated pi-electron system. Theheteroalicyclic may be substituted or unsubstituted. When substituted,the substituted group can be, for example, lone pair electrons, alkyl,trihaloalkyl, alkenyl, alkynyl, cycloalkyl, aryl, heteroaryl,heteroalicyclic, halo, nitro, azo, hydroxy, alkoxy, thiohydroxy,thioalkoxy, cyano, and amine. Representative examples are piperidine,piperazine, tetrahydro furane, tetrahydropyrane, morpholino and thelike.

A “hydroxy” group refers to an —OH group.

-   -   An “azide” group refers to a —N═N≡N group.    -   An “alkoxy” group refers to both an —O-alkyl and an        —O-cycloalkyl group, as defined herein.    -   An “aryloxy” group refers to both an —O-aryl and an        —O-heteroaryl group, as defined herein.    -   A “thiohydroxy” group refers to an —SH group.    -   A “thioalkoxy” group refers to both an —S-alkyl group, and an        —S-cycloalkyl group, as defined herein.    -   A “thioaryloxy” group refers to both an —S-aryl and an        —S-heteroaryl group, as defined herein.    -   A “halo” group refers to fluorine, chlorine, bromine or iodine.    -   A “trihaloalkyl” group refers to an alkyl substituted by three        halo groups, as defined herein. A representative example is        trihalomethyl.    -   An “amino” group refers to an —NR′R″ group where R′ and R″ are        hydrogen, alkyl, cycloalkyl or aryl.    -   A “nitro” group refers to an —NO₂ group.    -   A “cyano” group refers to a —C≡N group.

Representative examples of homodipeptides which can be used include,without limitation, naphthylalanine-naphthylalanine (nal-nal),(pentafluoro-phenylalanine)-(pentafluoro-phenylalanine),(iodo-phenylalanine)-(iodo-phenylalanine), (4-phenylphenylalanine)-(4-phenyl phenylalanine) and(p-nitro-phenylalanine)-(p-nitro-phenylalanine), see Examples 4, 5 andFIGS. 8-10.

As used herein in the specification and in the claims section below theterm “amino acid” or “amino acids” is understood to include the 20naturally occurring amino acids; those amino acids often modifiedpost-translationally in vivo, including, for example, hydroxyproline,phosphoserine and phosphothreonine; and other unusual amino acidsincluding, but not limited to, 2-aminoadipic acid, hydroxylysine,isodesmosine, nor-valine, nor-leucine and ornithine. Furthermore, theterm “amino acid” includes both D- and L-amino acids.

The nanostructures which can be used in the present embodiments arepreferably generated by allowing a highly concentrated hydrophilicsolution of the peptides of the present embodiments to self-assembleunder mild conditions. The resulting nanostructures are preferablystable under acidic and/or basic pH conditions, a wide range oftemperatures (e.g., 4-400° C., more preferably 2-200° C.) and/orproteolytic conditions (e.g., proteinase K).

It was found by the present Inventor that the peptide nanostructures aresufficiently stable to allow integration of the peptide nanostructuresinto polymer fibers during manufacturing process of fibers or otherarticles.

Depending on the number and type of amino acids used, the nanostructurecan be insulators, conductors or semiconductors. The nanostructure ofthe present embodiments can also be utilized as carriers onto whichatoms of different materials (e.g., conductive materials, chemical orbiological agents, etc.) may be incorporated.

According to preferred embodiments of the present invention, thenanostructures are filled or partially filled with at least one material(i.e., the nanostructures enclose or partially enclose the material).The material can be composed of a conducting material, a semiconductingmaterial, a thermoelectric material, a magnetic material (paramagnetic,ferromagnetic or diamagnetic), a light-emitting material, a gaseousmaterial, a biomineral, a polymer and/or an organic material.

For example, the nanostructures may enclose conducting or semiconductingmaterials, including, without limitation, inorganic structures such asGroup IV, Group III/Group V, Group II/Group VI elements, transitiongroup elements, or the like.

As used herein, the term “Group” is given its usual definition asunderstood by one of ordinary skill in the art. For instance, Group IIelements include Zn, Cd and Hg; Group III elements include B, Al, Ga, Inand Tl; Group IV elements include C, Si, Ge, Sn and Pb; Group V elementsinclude N, P, As, Sb and Bi; and Group VI elements include O, S, Se, Teand Po.

Thus, for conducting materials, the nanostructures may enclose, forexample, silver, gold, copper, platinum, nickel or palladium. Forsemiconducting materials the nanostructures may enclose, for example,silicon, indium phosphide, gallium nitride and others.

The nanostructures may also encapsulate, for example, any organic orinorganic molecules that are polarizable or have multiple charge states.For example, the nanostructures may include main group and metalatom-based wire-like silicon, transition metal-containing wires, galliumarsenide, gallium nitride, indium phosphide, germanium, or cadmiumselenide structures.

Additionally, the nanostructure of the present embodiments may enclosevarious combinations of materials, including semiconductors and dopants.Representative examples include, without limitations, silicon,germanium, tin, selenium, tellurium, boron, diamond, or phosphorous. Thedopant may also be a solid solution of various elemental semiconductors,for example, a mixture of boron and carbon, a mixture of boron and P, amixture of boron and silicon, a mixture of silicon and carbon, a mixtureof silicon and germanium, a mixture of silicon and tin, or a mixture ofgermanium and tin. In some embodiments, the dopant or the semiconductormay include mixtures of different groups, such as, but not limited to, amixture of a Group III and a Group V element, a mixture of Group III andGroup V elements, a mixture of Group II and Group VI semiconductors.Additionally, alloys of different groups of semiconductors may also bepossible, for example, a combination of a Group II-Group VI and a GroupIII-Group V semiconductor and a Group I and a Group VII semiconductor.

Specific and representative examples of semiconducting materials whichcan be encapsulated by the nanostructure of the present embodimentsinclude, without limitation, CdS, CdSe, ZnS and SiO₂.

The nanostructure of the present embodiments may also enclose athermoelectric material that exhibits a predetermined thermoelectricpower. Preferably, such a material is selected so that the resultingnanostructure composition is characterized by a sufficient figure ofmerit. Such composition may be used in thermoelectric systems anddevices as heat transfer media or thermoelectric power sources.According to a preferred embodiment of the present invention thethermoelectric material which can be encapsulated in the nanostructureof the present embodiments may be a bismuth-based material, such as, butnot limited to, elemental bismuth, a bismuth alloy or a bismuthintermetallic compound. The thermoelectric material may also be amixture of any of the above materials or other materials known to havethermoelectric properties. In addition the thermoelectric material mayalso include a dopant. Representative examples include, withoutlimitation, bismuth telluride, bismuth selenide, bismuth antimonytelluride, bismuth selenium telluride and the like. Other materials aredisclosed, for example, in U.S. Patent Application No. 20020170590.

As stated, the nanostructure of the present embodiments may also enclosemagnetic materials. Generally, all materials in nature posses some kindof magnetic properties which are manifested by a force acting on aspecific material when present in a magnetic field. These magneticproperties, which originate from the sub-atomic structure of thematerial, are different from one substrate to another. The direction aswell as the magnitude of the magnetic force is different for differentmaterials.

Whereas the direction of the force depends only on the internalstructure of the material, the magnitude depends both on the internalstructure as well as on the size (mass) of the material. The internalstructure of the materials in nature, to which the magneticcharacteristics of matter are related, is classified according to one ofthree major groups: diamagnetic, paramagnetic and ferromagneticmaterials, where the strongest magnetic force acts on ferromagneticmaterials.

In terms of direction, the magnetic force acting on a diamagneticmaterial is in opposite direction than that of the magnetic force actingon a paramagnetic or a ferromagnetic material. When placed in externalmagnetic field, a specific material acquires a non-zero magnetic momentper unit volume, also known as a magnetization, which is proportional tothe magnetic field vector. For a sufficiently strong external magneticfield, a ferromagnetic material, due to intrinsic non-local ordering ofthe spins in the material, may retain its magnetization, hence to becomea permanent magnet. As opposed to ferromagnetic materials, bothdiamagnetic and paramagnetic materials loose the magnetization once theexternal magnetic field is switched off.

Representative examples of paramagnetic materials which can be enclosedby the nanostructure of the present embodiments include, withoutlimitation, cobalt, copper, nickel and platinum. Representative examplesof ferromagnetic materials include, without limitation, magnetite andNdFeB.

Other materials which may be encapsulated by the nanostructure of thepresent embodiments include, without limitation, light-emittingmaterials (e.g., dysprosium, europium, terbium, ruthenium, thulium,neodymium, erbium, ytterbium or any organic complex thereof),biominerals (e.g., calcium carbonate), polymers (e.g., polyethylene,polystyrene, polyvinyl chloride, polynucleotides and polypeptides,thermoplastics, fluorescent materials or other colored materials.

In order to generate the filled nanostructure of the presentembodiments, the foreign material is introduced into the internal cavityof the nanostructure, to encapsulate the material in nanostructure.

Exemplified methods for filling nanostructure are described in“Capillarity-induced filling of carbon nanotubes”, P M Ajayan et al.,Nature, vol. 361, 1993, pp. 333-334; “A simple chemical method ofopening and filling carbon nanotubes”, SC Tsang et al., Nature, vol.372, 1994, pp. 159-162; and U.S. Pat. Nos. 5,916,642 and 6,361,861.

Following are representative examples of spinning methods which can beused in various preferred embodiments of the present invention.

In the embodiment in which electrospinning is employed, the solutionwith the peptide nanostructures is extruded, for example under theaction of hydrostatic pressure, through capillary apertures of adispenser, which is spaced apart from a precipitation electrode. Thedispenser and precipitation electrode are kept at different electricalpotentials thus forming an electric field therebetween. Under the effectof electrical force, jets depart from the dispenser and travel towardsthe precipitation electrode. Moving with high velocity in theinter-electrode space, the jet cools or solvent therein evaporates, thusforming fibers which are collected on the surface of the precipitationelectrode.

In the embodiment in which a wet spinning process is employed, thesolution with the peptide nanostructure of the present embodiments isextruded through a spinneret, under the action of mechanical forces(e.g., pressure, gravity). The formed fiber(s) can then be collectedusing a suitable take up device, e.g., a drum.

In the embodiment in which a dry spinning process is employed, thesolution with the peptide nanostructures of the present embodiments isextruded through a spinneret, and solvent therein is rapidly evaporatedby inert gas. Similarly to the above, the formed fiber(s) can becollected using a take up device.

In the embodiment in which tack spinning is employed, the solution ispreferably prepared in a tack state. This can be done, for example, bymixing the solution with certain polymeric additives which facilitatethe adherence of the solution to a surface. Once prepared, the solutionwith the peptide nanostructures is pressed against a heated surface,such as, but not limited to, a heated roll. The solution can then beseparated from the surface and cooled by blowing cold air or anothercooling medium into a nip formed between the heated surface and thesolution as the solution is separated from the surface. The separationand cooling of the solution result in drawing of fibrils out from thesurface.

In any event, once the fibers are formed and collected, they can beunwound off the take up device, if desired, for example, for packing orstorage purposes or for uploading to another apparatus.

It is expected that during the life of this patent many relevantspinning processes will be developed and the scope of the term spinningprocesses is intended to include all such new technologies a priori.

Performing the above method according to present embodimentssuccessfully produces one or more fibers. Therefore, according toanother aspect of the present invention there is provided a fiber ofpeptide nanostructures. In accordance with preferred embodiments of thepresent invention the fiber is at least 100 nm, more preferably at least1 μm, more preferably at least 10 μm in length. The fiber can containany of the aforementioned peptide nanostructures.

The fibers of the present embodiments can be used for forming nonwovenarticles. This can be done, for example, by repeating the selectedspinning process a plurality of times and allowing the formed fiber toprecipitate on a suitable precipitation device thus forming the nonwovenarticle thereupon. As will be appreciated by one ordinarily skilled inthe art, when a relative motion is established between the formedfiber(s) and the precipitation device, a nonwoven mat of fibers made ofpeptide nanostructures is formed.

Reference is now made to FIG. 2 which is a flowchart diagram of a methodsuitable for forming a film of peptide nanostructures, according to apreferred embodiment of the present invention. The method begins at step20 and continues to step 22 in which peptide molecule are placed in anorganic solvent. The method continues to step 24 in which an hydrophilicsolvent (e.g., water) is added to the organic solvent, such that aninterface is formed between the organic and hydrophilic solvents. Themethod then proceeds to step 26 in which the organic and hydrophilicsolvents are incubated under conditions which allow the peptidemolecules to form a film of peptide nanostructures in the formedinterface. The incubation conditions are such that the nanostructuresare self-assembled as further detailed hereinabove.

The method ends at step 28.

Reference is now made to FIG. 3 which is a flowchart diagram of a methodsuitable for forming one or more layers of peptide nanostructures,according to another preferred embodiment of the present invention. Themethod begins at step 30 and continues to step 32 in which peptidenanostructures are placed in an organic solvent.

The method continues to step 34 in which one or more droplets of theorganic solvent are applied onto a surface of an hydrophilic solvent.The method then continues to step 36 in which pressure is applied on thedroplet of organic solvent, so as to form a layer of peptidenanostructures on the surface.

The application of pressure is preferably by moving barriers which canbe made, for example, from Teflon®. The barriers reduce the surface areaof the film and as a consequence the surface pressure of the layerincreases. The pressure-area isotherm can be monitored continuously,e.g., by monitoring the surface are of the layer and measuring the forceapplied by the barrier. When pressure reaches some predetermined level,the barriers are stopped such that the layer is substantially in asteady state.

The layers can then be transferred to a substrate by any way known inthe art, for example, the Langmuir-Blodgett technique or theLangmuir-Schaeffer technique.

When a Langmuir-Blodgett technique is employed, the substrate ispreferably immersed a vertically through the layer. The substrate isthen pulled up and the layer is transferred onto the substrate bylateral compression.

When a Langmuir-Schaeffer is employed, the substrate is descendedhorizontally onto the layer. Once a contact is made between the layerand the substrate, the substrate is extracted with the layer on it.

According to a preferred embodiment of the present invention the filmcan be subjected to a doping procedure. Doping procedures are known inthe art and are found, for example, in the Handbook for conductivepolymers, Edited by Terje A. Skotheim Vol. 1, 1986. This embodiment isparticularly useful when it is desired to form a film with conductiveproperties.

Reference is now made to FIG. 4 which is a flowchart diagram of a methodsuitable for forming an array or film of peptide nanostructures on asubstrate, according to a preferred embodiment of the present invention.The method begins at step 40 and continues to step 42 in which peptidemolecule are placed in an organic solvent, such as, but not limited to,Hexaflorupropanol. The method continues to step 44 in which the organicsolvent is applied on a substrate, such as, but not limited to, asiliconized glass an ITO glass and the like. The method then proceeds tostep 46 in which the substrate is incubated under conditions which allowthe peptide molecules to form an array or film of peptide nanostructureson the substrate. The incubation conditions are preferably such that thenanostructures are self-assembled as further detailed hereinabove.

When the nanostructures are responsive to a magnetic and/or electricfield (i.e., when a magnetic and/or electric field exerts a force on thenanostructures), the method preferably continues to step 48 in which thesubstrate is subjected to a magnetic and/or electric field. Theadvantage of this embodiment, is that the forces can facilitate theassembling and/or alignment of the nanostructures on the substrate. Step48 can be executed subsequently or contemporaneously with step 46.

The method ends at step 49.

Performing one or more of the above methods according to presentembodiments successfully produces a thin film of peptide nanostructures.In accordance with preferred embodiments of the present invention, thethin film is at least 100 nm², more preferably at least 1 μm², morepreferably at least 10 μm² in area size.

Additional objects, advantages and novel features of the presentinvention will become apparent to one ordinarily skilled in the art uponexamination of the following examples, which are not intended to belimiting. Additionally, each of the various embodiments and aspects ofthe present invention as delineated hereinabove and as claimed in theclaims section below finds experimental support in the followingexamples.

EXAMPLES

Reference is now made to the following examples, which together with theabove descriptions illustrate the invention in a non limiting fashion.

Example 1

Thin film of peptide nanostructures was manufactured, in accordance withpreferred embodiments of the present invention.

The manufacturing process is shown in FIGS. 5A-C. In a first step, shownin FIG. 5A, Boc-FF—COOH dipeptide was dissolved in benzene to aconcentration of 10 mg/ml and placed in a reaction beaker. In a secondstep, shown in FIG. 5B, a water solution was added into the reactionbeaker. As shown in FIG. 5B, an interface was formed between the benzeneand the water solution. The benzene and the water solution wereincubated for several hours. FIG. 5C shows a film of Boc-FF—COOHdipeptide which was formed at the interface after incubation.

Example 2

The Langmuir-Blodgett technique was employed to manufacture a thin filmof peptide nanostructures, in accordance with preferred embodiments ofthe present invention.

A droplet of Boc-FF—COOH dipeptide was dissolved in chloroform-methanol(9:1) to a concentration of 1 mg/ml. The resulted solution was thenapplied on a surface of water in a Langmuir-Blodgett trough. Movingbarriers, positioned at the ends of the trough were used to applypressure on the droplet, and a film of nanostructures was formed.

FIG. 6 shows a pressure-area isotherm obtained while applying thepressure. As shown in FIG. 6, the surface tension increases when thesurface area is decreased, and peptide molecules are assembled togetherinto a monolayer, which is further compressed into a film.

Example 3

An array of peptide nanostructures was manufactured on a substrate, inaccordance with preferred embodiments of the present invention.

Diphenylalanine peptide was dissolved to a concentration of 100 mg/ml in1,1,1,3,3,3-Hexafluoropropanol. 30 μl of the solution were applied ontosiliconized glass and let to dry in room temperature.

FIGS. 7A-B are a low magnification (FIG. 7A) and a high magnification(FIG. 7B) images of the substrate, obtained using a high-resolutionscanning electron microscope. As shown in FIGS. 7a-b , an aligned arrayof peptide nanotubes was formed on the substrate.

Example 4

Tubular nanostructures were formed from naphthylalanine-naphthylalanine(Nal-Nal) dipeptides, in accordance with preferred embodiment of thepresent invention. The Chemical structure of the (Nal-Nal) dipeptide isschematically shown in FIG. 8.

Fresh stock solutions of Nal-Nal dipeptides were prepared by dissolvinglyophilized form of the peptides in 1,1,1,3,3,3-hexafluoro-2-propanol(HFIP, Sigma) at a concentration of 100 mg/mL. To avoid anypre-aggregation, fresh stock solutions were prepared for eachexperiment.

The peptides stock solutions were diluted into a final concentration of2 mg/mL in double distilled water, then the samples were placed on 200mesh copper grid, covered by carbon stabilized formvar film. Following 1minute, excess fluid was removed and the grid was negatively stainedwith 2% uranyl acetate in water. Following 2 minutes of staining, excessfluid was removed from the grid. Samples were viewed in JEOL 1200EXelectron microscope operating at 80 kV.

FIG. 9 is an electron microscope image of the samples, captured a fewminutes after the dilution of the peptide stock into the aqueoussolution. As shown, the dipeptides form thin (from several nanometers toa few tens of nanometers in diameter) and elongated (several microns inlength) tubular structures.

Example 5

Tubular and planar nanostructures were formed from by four differentdipeptides, in accordance with preferred embodiment of the presentinvention.

The following dipeptides were used:(Pentafluoro-Phenylalanine)-(Pentafluoro-Phenylalanine),(Iodo-Phenylalanine)-(Iodo-Phenylalanine), (4-Phenylphenylalanine)-(4-Phenyl phenylalanine) and(P-nitro-Phenylalanine)-(P-nitro-Phenylalanine).

For the first two dipeptides[(Pentafluoro-Phenylalanine)-(Pentafluoro-Phenylalanine) and(Iodo-Phenylalanine)-(Iodo-Phenylalanine)] fresh stock solutions wereprepared by dissolving lyophilized form of the peptides in DMSO at aconcentration of 100 mg/mL.

For the third and fourth dipeptides [(4-Phenyl phenylalanine)-(4-Phenylphenylalanine) and (P-nitro-Phenylalanine)-(P-nitro-Phenylalanine)],fresh stock solutions were prepared by dissolving lyophilized form ofthe peptides in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP, Sigma) at aconcentration of 100 mg/mL. To avoid any pre-aggregation, fresh stocksolutions were prepared for each experiment.

The peptides stock solutions were diluted into a final concentration of2 mg/mL in double distilled water.

In the case of (P-nitro-Phenylalanine)-(P-nitro-Phenylalanine) the finalconcentration was 5 mg/mL.

Subsequently, the samples were placed on 200 mesh copper grid, coveredby carbon stabilized formvar film. Following 1 minute, excess fluid wasremoved and the grid was negatively stained with 2% uranyl acetate inwater. Following 2 minutes of staining, excess fluid was removed fromthe grid. Samples were viewed in JEOL 1200EX electron microscopeoperating at 80 kV.

FIGS. 10A-D are electron microscope images of the four samples, captureda few minutes after the dilution of the peptide stock into the aqueoussolution.

FIG. 10A shows tubular assemblies formed by the(Pentafluoro-Phenylalanine)-(Pentafluoro-Phenylalanine)dipeptide, FIG.10B shows tubular structures assembled by(Iodo-Phenylalanine)-(Iodo-Phenylalanine), FIG. 10 C shows planarnanostructures formed by (4-Phenyl phenylalanine)-(4-Phenylphenylalanine), and FIG. 10D shows fibrilar assemblies of(P-nitro-Phenylalanine)-(P-nitro-Phenylalanine).

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims. All publications, patents and patentapplications mentioned in this specification are herein incorporated intheir entirety by reference into the specification, to the same extentas if each individual publication, patent or patent application wasspecifically and individually indicated to be incorporated herein byreference. In addition, citation or identification of any reference inthis application shall not be construed as an admission that suchreference is available as prior art to the present invention.

What is claimed is:
 1. A fiber comprising a plurality of peptidenanostructures, wherein each peptide in each of said plurality ofpeptide nanostructures comprises no more than 4 amino acids, at leastone of said 4 amino acids being an aromatic amino acid, the fiber beingat least 100 nm in length.
 2. The fiber of claim 1, wherein at least oneof said peptides comprises at least two aromatic amino acids.
 3. Thefiber of claim 2, wherein each peptide in each of said peptidenanostructures is a homodipeptide.
 4. The fiber of claim 1, wherein saidnanostructures at least partially enclose a material therein.
 5. Thefiber of claim 1, being producible by subjecting said peptidenanostructures, in solution, to an electric field.
 6. The fiber of claim5, being collected on a precipitation electrode.
 7. The fiber of claim6, being collected on a precipitation electrode by rotating saidprecipitation electrode so as to wind the fiber around saidprecipitation electrode.
 8. The fiber of claim 6, being collected on aprecipitation electrode by moving the fiber relative to saidprecipitation electrode so as to provide a nonwoven mat of said peptidenanostructures.
 9. A nonwoven article comprising a plurality ofelectrospun fibers, wherein at least one of said plurality ofelectrospun fibers is the fiber of claim
 1. 10. The fiber of claim 9,wherein at least one of said peptides comprises at least two aromaticamino acids.
 11. The nonwoven article of claim 9, wherein each peptidein each of said peptide nanostructures is a homodipeptide.